import pandas as pd

def read_csv_ivstng(filepath):
    df = pd.read_csv(filepath)
    df['日期'] = df['日期'].apply(lambda x: pd.datetime.strptime(x, u'%Y年%m月%d日'))
    df['日期'] = df['日期'].apply(lambda x: pd.datetime.strftime(x, u'%Y%m%d'))
    df.set_index('日期', inplace=True)
    df.sort_index(inplace=True)
    return df

